In general, a display device is monitors for TV or computers, and includes a display diode that forms an image and a case that supports the display diode.
As a display diode, there may be exemplified by plasma display panel (PDP), liquid crystal display (LCD), electrophoretic display and cathode-ray tube (CRT). In a display diode, an RGB pixel pattern and additional optical filter for implementing an image may be provided.
An optical filter may include at least one of an anti-reflective film that prevents the reflection of the light that is incident from an outside to the outside, a near IR shield film that shields near infrared light that is generated in a display diode in order to prevent the disoperation of electronic devices such as remote controllers and the like, a color correction film that includes a color control dye and increases a color purity by controlling a color tone, and an electromagnetic wave shield film that shields an electromagnetic wave that is generated in a display diode when a display device is driven. An electromagnetic wave shield film includes a transparent substrate and a metal mesh pattern that is provided on the substrate.
Recently, according to the rapid spreading of IPTVs, a demand for touch function that a direct input device uses without a separate input device such as remote controllers has been increased. In addition, a function for specific point recognition and multi-touch function that can perform writing are required.
A touch panel may be classified into a resistive type touch panel, a capacitive type touch panel and an electromagnetic type touch panel. A resistive type touch panel detects the position that is pressed by a pressure by detecting a change in current or voltage value, in response to the application of a direct voltage. A capacitive type touch panel uses a capacitance coupling in a state where an alternating voltage is applied. An electromagnetic type touch panel detects the selected position by a change in voltage in a state where a magnetic field is applied.
Among them, the resistive type and capacitive type touch panels recognize the touch by a change in electric contact or capacitance by using a transparent conductive film such as the ITO film. However, since a transparent conductive film has the high resistance of 100 ohms/square or more, the sensitivity is lowered when it is manufactured in a large scale. Further, a high cost of ITO film makes the commercialization of a large-scale screen. In order to reduce a manufacturing cost, there is an effort to adopt a metal pattern on a touch panel.
When a display device includes an electromagnetic wave shield film or a touch panel that includes a metal pattern, a Moire phenomenon may be caused by the interference between the metal pattern and a pixel pattern of the display, electrode pattern or pattern structure of the other optical film. Here, the Moire phenomenon means an interference fringe generated when two or more regular patterns overlap.
In a plasma display panel (PDP), since a pixel pattern of the plasma display panel (PDP) and a metal mesh pattern for electromagnetic wave shielding of an optical filter coexist, a Moire phenomenon may occur. Therefore, in general, if a specification of the plasma display panel (PDP) is determined, an effort for solving the Moire phenomenon is required.
In order to remove a Moire phenomenon, the line width and pitch and angle of the metal mesh pattern for the electromagnetic wave shielding are controlled, but there is a problem in that it should correspond to different patterns according to the size and the pixel implementation method of the display device.
A plasma display panel that is currently developed, in order to implement high resolution, includes a more precise pixel pattern, such that the occurrence possibility of a Moire phenomenon is increased. Accordingly, there is a limit in improvement of the Moire phenomenon by using only the line width, pitch, and angle of the known pattern.